1. Field of the Invention
The present invention is concerned with a process and a device for effectively utilizing exhaust heats in connection with high-power engines in particular with an antifreeze system for preventing the formation of ice in the air intake systems of an energetic gas turbine.
2. The Prior Art
Such antifreeze systems of energetic gas turbines are well-known in the state of the art. In connection with the known antifreeze system for preventing icing and undercooling in the operating air intake and filter systems of the turbine, as well as in the generator cooling system, a part current of air is withdrawn downstream of a compressor, which serves for supplying the combustion chamber for the turbine. Said withdrawn part current of air effects a reduction in the performance, which is caused by both the increase in the intake temperature and the not insignificant withdrawal of air at the end of the compressor. This, of course, has an adverse effect on the overall energy balance of the operating system for generating the respective form of energy.
The power engine (generator) generating the energy is generally driven by a gas turbine, whereby the compressor, the combustion chamber and the turbine are accommodated in a common housing. The operating machine, in the present case a gas turbine, requires as operating medium great amounts of external air, which has to be subjected to filtration. The power engine, in the present case a generator, heats up considerably in the course of the operation and, therefore, has to be cooled with the help of a special gas cooling system. As a rule, external air is used as gas, whereby the problem arises that at certain excessively low outside temperatures and excessively high relative air humidity, ice may form in the total air intake system, which may lead to considerable damaging effects in the operating system. In order to prevent such formation of ice, provision is made in the state of the art that when the heat requirement increases, i.e., at dropping outside temperatures, hot air is withdrawn at the end of the compressor via a defined control valve, and then readmitted into the air inlet system. It is possible with the help of this measure to maintain the temperature in the region of the air inlet of the air intake system between about 3xc2x0 C. and 5xc2x0 C. The amount of gas withdrawn from the compressor comes in this connection to approximately 5 kg/s at a temperature of 400xc2x0 C. Less operating air is thus available to the gas turbine, which finally reduces the electric terminal power on the generator.
As such power losses are not inconsiderable, the object of the present invention is to at least minimize the power losses due to the application of antifreeze devices.
Therefore, the object of the present invention is to make available a process and a device which minimize the losses of the effective capacity of the power machine with rising heat requirements in the antifreeze system of gas turbine installations.
The process as defined by the invention for preventing the formation of ice in the gas mixture conduit systems with the use of already heated gas in the total operating system is characterized in that heat is withdrawn in a defined sequence at energetically favorable points in a way such that the effective capacity of the operating system is optimized.
The device operating according to the process as defined by the invention is characterized by
a multiway gas conduction system, which allocates the streams of gas to different conduits, and which is arranged in the exhaust air duct of the cooling system of the power engine;
a controlling system for withdrawing heat on the off-heat system of the operating system; and
a bypass conduit with a control valve between the outlet of the gas compressor and the gas inlet opening of the air intake and cooling system.
An advantageous sequence of heat withdrawal in the form of heat already heated in the operating system is that the heated generator exhaust air exiting from the power machine is first supplied to the air intake system, and when the heat requirement rises further, the heat of the off-heat system is then withdrawn at the end of the heat circulation of the operating system, and, as a further possibility, the heat of the gas compressor system is withdrawn. An advantageously suitable point for withdrawing heat from the off-heat system is the site where the gas temperature is between 120xc2x0 C. and 200xc2x0 C. Furthermore, it is advantageous if the heat is withdrawn from the off-heat system downstream of the heat exchangers of the process connected downstream; however, the temperature level has to be sufficiently high.
Also, it is advantageous to conduct the heated generator air via a multiway gas conduction system, whereby such multiway gas conduction system is a three-way control valve, as a rule.
Furthermore, it is advantageous to conduct the heat of the off-heat system via a controlling device, so that the heat requirement to be withdrawn can be controlled according to a defined specification.
If the heat requirement rises further, or if the first two part systems fail, or if special operating cases occur, a defined amount of heat has to be withdrawn according to the invention at the end of the compressor, so that the operating temperature is maintained at from 3xc2x0 C. to 5xc2x0 C. in order to prevent the formation of ice in the air intake system.
The heat to be withdrawn in the individual heat systems has to be determined according to the invention pursuant to a defined functional specification. An advantageous mixing ratio of generator exhaust air:off-heat gas:external air is given if the relative air humidity does not reach its maximum value in the critical spots in the air intake system. In the determination of the optimal mixing ratio of the individual streams of gas, the further calculations are advantageously and, according to the invention, governed by various parameters such as, for example the outside air temperature (Ta) and the relative air humidity (Wrel). Said parameters, of course, are specified only by way of example, and are supplemented by a great number of additional important and required parameters in the determination function.
The advantageous regulation of the streams of gas in the individual heat feed conduits is controlled with defined setting elements such as control valves and air flaps.